Ezrow, Homola and Tavits. “When Extremism Pays.” Journal of Politics. Supplementary Appendix The meaning of Left and Right across time and space (footnote 13) Several studies suggest that the patterns of ideological structuring underlying the left-right scale may differ between Eastern and Western Europe (e.g., Evans and Whitefield 1993) as well as across countries and time (Evans and Whitefield 1998; Harbers, De Vries, and Steenbergen 2012; Linzer 2008; Markowski 1997). Nevertheless, there are strong arguments that suggest the left-right ideological dimension can be a useful framework for analyzing political competition in post-communist democracies. Marks et al. (2006: 169) report that the “theory of party positioning developed for Western European political parties does, indeed, apply to Central and Eastern Europe.” Survey-based studies suggests that respondents in postcommunist Europe are as likely to place themselves on the left-right scale as in other countries, and to base their voting decision on these positions (Pop-Eleches and Tucker 2010, 2011; see also McAllister and White 2007). Rohrschneider and Whitefield (2012, 92-93) similarly state, “The results make plain that citizens in W[estern] E[urope] and CEE have, broadly viewed, developed a similar understanding of left-right ideology regarding the economic dimension.”1 Additionally, Linzer (2008), using a cross-national sample of countries, demonstrates that voters’ interpretation of the left-right scale is likely to differ across countries. Harbers, De Vries and Steenbergen (2012) reach a similar conclusion studying three Latin American countries. However, Linzer does not find that the CEE countries are systematically different from their western neighbors: the left-right spectrum structures public opinion in some countries better than others within both regions. For example, based on evidence presented on p. 122, left-right has a stronger role in structuring public opinion in Bulgaria, Czech Republic, and Germany than in France, Poland, and Italy. We account for any possible cross-country differences by conducting a number of additional robustness checks. First, we normalize the policy distance by the distribution of voter preferences (measured by the standard deviation of left-right self-placements) and the average party distance in a political system (given in Equation 3 and 4 on pp. 13-14 of the manuscript). In alternative analyses, presented below (see Tables S2f-S4g, pp. S13-S16), we also (a) control for country fixed effects and (b) cluster standard errors by country. These analyses compare parties within the same system (not across systems), i.e., they compare the electoral fate of extremists vs. moderates in the same country, within the same left-right context. These additional analyses make it especially clear that our findings are not directly affected by any cross-national differences in the meaning of left-right. 1 The authors also find that in WE (but not in CEE), the left-right dimension also correlates well with “new politics” issues (e.g. immigration, attitudes towards same-sex couples), which suggests that these countries are still in the process of incorporating these issues into their national debates, along the lines of the “issue evolution” literature in the United States (Carmines and Stimson 1989) and Europe (De Vries 2007). S-1 Ezrow, Homola and Tavits. “When Extremism Pays.” Journal of Politics. Individual-level analyses (footnote 22) We performed a series of additional individual-level analyses in order to evaluate whether the arguments that we make in the paper also hold on the individual level. We thank an anonymous reviewer for encouraging us to explore these relationships. Specifically, focusing on the party level, we have argued the following: (a) uncertainty repels voters, (b) centrist positions generate uncertainty, and (c) extremism is especially likely to reduce uncertainty in new democracies. Given this, we also expected that, in new democracies, non-centrist policy positions are likely to be electorally more beneficial than the centrist ones. Note that because our arguments and expectations in the main text are cast at the party level, there is a danger of committing ecological fallacy by trying to deduce individual-level relationships from the correlation of the variables collected at the party level. Still, since several of these arguments (especially (a) and (b)) draw on assumptions about individual level behavior, we will here provide preliminary tests of these relationships at the individual level. Specifically, we will explore whether (a) a voter is less likely to support a party the more ambiguous (i.e., less certain) its position, and (b) a voter is more certain about the positions of non-centrist parties (and especially so in new democracies). Finally, we will test whether an individual voter is more likely to vote for a more extreme than a moderate party. The results of these individual level analyses are generally consistent with the aggregate level results reported in the main text. We would like to stress, though, that these results are preliminary. A full exploration of the individual-level relationships (including developing more explicitly an individual-level theory and building more extensive individual- level models) remains beyond the scope and purpose of our paper and would require a separate study. We also note in the results that we report below, and as we comment in the conclusion of the main text, that follow up studies will need to do more to explain the cross-national findings that we report in the paper. Uncertainty repels voters (Individual-level analyses that correspond to Table 4 in text) We found that parties whose positions are uncertain attract less electoral support. The individual level assumption underlying this conclusion is that a voter is less likely to support a party whose position is uncertain. Therefore, we need to estimate vote choice based on the level of certainty about party position. Including all parties from the 31 countries would require running separate conditional logit models for the 31 countries and trying to compare results from the 31 separate analyses. In order to avoid such non-trivial complication, we decided to concentrate only on the respondents that voted for one of the top two parties in the election (i.e., the parties with the highest and second highest totals). All other respondents (including those who did not indicate a vote choice) are dropped from the data set. We constructed the dependent variable [Voted top left] so that it equals 1 if the respondent voted for the top party on the left and 0 if the respondent voted for the top party on the right. This allows us to pool all the observations together and compare logit estimates directly. We construct a crucial independent variable that is designed to capture an electorate’s willingness to place the top left and top right party on the 0-10 left-right scale. Specifically, Relative willingness to place is calculated as follows: S-2 Ezrow, Homola and Tavits. “When Extremism Pays.” Journal of Politics. [Relative willingness to place]: [willingness in the electorate to place the top left party on the left-right scale] - [willingness in the electorate to place the top right party on the left- right scale] For all observations, we expect that the coefficient on Relative willingness to place will be positive. In other words, we expect that the higher the overall proportion of people in the electorate placing the top left party (as compared to the top right party), the higher the likelihood of an individual to vote for the left party (as compared to the right party). More certainty about party’s positions is associated with a higher likelihood of voting for it. In addition, we also include controls for age, gender, marital status, education, household income, and an index of political information.2 The parameter estimates for this model specification are reported in Table i4, and they support the assumption that individual voters are more likely to vote for a party whose position is certain. (This result also holds when the sample is split into postcommunist and advanced democracies and the effect is estimated separately for each.) Table i4. The Effect of Voter Certainty on Voting for the Top Left Party Advanced and postcommunist democracies Relative willingness to place 6.079*** (.376) Age -.001* (.001) Gender .078*** (.019) Marital status .011 (.009) Education -.001 (.006) Household income -.076*** (.008) Political knowledge -.032*** (.009) Constant .294*** (.067) N 46703 Pseudo-R2 .007 Note: Table entries are coefficients from a logit model with standard errors in parentheses. The dependent variable is Voted top left. *p < .10, **p < .05, ***p < .01, two-tailed test. 2 The index is based on a battery of three “knowledge” questions that each CSES survey includes. Despite considerable variation in terms of content and format across the different surveys, these questions provide the best proxy for political knowledge (see Elff 2009). The final measure is an additive index of the three items with correct answers to each of the items coded as 1 and wrong answers as 0. S-3 Ezrow, Homola and Tavits. “When Extremism Pays.” Journal of Politics. Extremism reduces uncertainty (especially in new democracies) (Individual-level analyses that correspond to Table 3) According to the results presented in Table 3, extreme policy positioning increases voter certainty about party positions, and the effect is stronger for postcommunist democracies more than for the established ones. On the individual level, this presumes that an individual voter is more certain about the position of an extremist than a centrist party. Accordingly, we estimate the probability of a respondent’s willingness to place a focal political party on an ideological scale. The dependent variable, Willing to place, equals 1 if the respondent placed the party on the 0-10 left-right scale, and 0 otherwise.